Originally Posted by jojo
Who routinely does that?
We don't know, because so far, we have not been tracking weakly hit ground balls.
Right now, we track ground balls, which are defined as any hit ball that touches the ground before it touches a fielders mitt; flyballs and line drives, which are defined by the trajectory of the ball. These definitions tells us very little about how hard a ball was hit.
Many ground balls are hit harder than flyballs, and even line drives. Even many infield popups are very hard hit, basically homers that are just missed. So, just by looking at a pitcher's GB/FB/LD lines, we cannot with any accuracy tell how hard his pitches are being hit.
Now there has been a bit of research been done on the velocity of ball as it leaves the bat, but not enough to be able to draw any real conclusions. I do think that when that technology becomes more accessible, and more data like that accumulates, we will learn much more about pitching than we currently do.